The present invention relates to the art of cable and more particularly to a color cable and the manufacturing method therefor.
Conventionally, manufacture of an electrical signal or current transmitting cable comprises the step of surrounding a strand of conductor by an insulated cylinder of opaque plastic material using extrusion molding techniques. Color versions of such a cable are obtained by adding a color additive to the plastic material. However, this design suffers from the disadvantage that the color of cable, whether monotonous or irregular, is determined solely by the additive to the plastic material of the outer insulated cylinder, and as a result it is not possible to provide a multi-colored cable, or a color cable in which the color or colors of individual strands or cables within the insulation may be viewed.
Another conventional transmission cable manufacturing technique is to surround a strand of conductor by a transparent plastic material in the form of a cylinder by extrusion molding. However, in the conventional design, color is still obtained by adding a color additive to the plastic material and, therefore, despite its transparency, the color of the cable is still determined solely by the additive to the material of the outer insulator. As a result, it is impossible to obtain a multi-colored cable through such a cable manufacturing technique.
One way to solve this problem is to provide a color cable and a manufacturing method therefor in which the cable comprises a conductor body having one or more conductors, one or more color windings uniformly wound around and secured to the conductor body by heating, and a transparent plastic covering formed on the winding by extrusion molding, as described in copending parent U.S. patent application Ser. No. 09/573,173. Using this method, a multi-colored cable can be obtained simply by changing the color or number of strands, and/or by changing windings during the winding process. The results may be purely decorative purpose or the color of the cable may be varied according to electrical specifications and usage, so that the user can recognize the same from the color of the cable.
However, despite the advantages of this method, several problems can still arise if the technique is not properly implemented:
First, if the thickness of the color windings is over 0.035 mm, the color cable will become inflexible, and the outer diameter of the cable will be difficult to maintain in a size small enough required specifications. In addition, the resulting cable will lack uniformity dues to thickness differences in the overlap region.
Second, if the thickness of the color windings is below 0.015 mm, the color windings will be too easily broken by the tension applied as the strip is wound onto the cable.
Third, if the width of the color windings is out of the range of 1-3 mm, the windings will be difficult to wind at a very high speed, and will be subject to folding, resulting in wrinkles that cause the cable to have a poor reflective color and a rough surface.
Fourth, if the overlapped region of the strip is over 50% if the width, the color cable will also have a rough surface, the outer diameter of the cable will be increased, and the material in the windings will in general be substantially wasted. On the other hand, if the overlapped region is below 20% of the width, the cable on which the windings are wound may become exposed upon bending, either resulting in a permanent gap or wrinkles.
It is accordingly a first objective of the invention to provide a color cable and a manufacturing method therefor in which the cable comprises a conductor body having one or more conductors, one or more color windings uniformly wound around and secured to the conductor body by heating, and a transparent plastic covering formed on the winding by extrusion molding, and which does not suffer from undue stiffness or size, wrinkling, of lack of uniformity, and yet that can easily be manufactured at high speed.
It is another object of the present invention to provide a color cable and the manufacturing method therefor wherein the color of the winding wound around the conductor body can be seen through the surrounded transparent plastic material, resulting in a colorful cable, and yet that is durable, flexible, uniform, and easily manufactured.
It is still another object of the present invention to provide a color cable and the manufacturing method therefor wherein the color of the cable can be varied according to electrical specifications and usage, so that a user can recognize the same from the color of cable, and yet that is durable, flexible, uniform, and easily manufactured.
These objectives are achieved, in accordance with the principles of a preferred embodiment of the invention, by providing a color cable and a manufacturing method therefor in which the cable comprises a conductor body having one or more conductors, one or more color windings uniformly wound around and secured to the conductor body by heating, and a transparent plastic covering formed on the winding by extrusion molding, and in which the conductor body includes at least one electrical signal or power transmission cable having at least one conductor, the winding has a thickness of between approximately 0.015 and 0.035 mm, a width of between approximately 1 and 3 mm, and is overlapped during winding to form an overlapped region of between approximately 20% and 50% of the width of the winding, and the transparent plastic covering is made of PET, PP, PVC, or PE.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.